JP2014106182A - Differential pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To completely prevent a joint part of a sensor chip from peeling and to achieve reduction in size by employing a simple structure.SOLUTION: In a meter body 12, a communication path (pressure lead path) 12g which guides measurement pressure P1 to a pressure reception diaphragm 14a for P1 protection and a communication path (pressure lead path) 12h which guides measurement pressure P2 to a pressure reception diaphragm 14b for P2 protection are formed. A space (recessed part 12e) on the back side of the pressure reception diaphragm 14a for P1 side protection and a sensor chamber are connected to each other by a communication path 12k and a space (recessed part 12f) on the back side of the pressure reception diaphragm 14b for P2 side protection and the sensor chamber are connected to each other by a communication path 12l; and a space including the recessed parts 12e, 12f, communication paths 12k, 12l, and sensor chamber together is defined as a sealed chamber and filled with a pressure transfer medium 20c.

Description

  The present invention relates to a differential pressure sensor using a sensor diaphragm that outputs a signal corresponding to a pressure difference.

  Conventionally, as an industrial differential pressure sensor, a differential pressure sensor using a sensor diaphragm that outputs a signal corresponding to a pressure difference is used. In this differential pressure sensor, each measurement pressure applied to the pressure receiving diaphragms on the high pressure side and the low pressure side is guided to one surface and the other surface of the sensor diaphragm by a sealing liquid as a pressure transmission medium, and distortion of the sensor diaphragm is, for example, It is configured to detect a change in the resistance value of the strain resistance gauge and to convert the resistance value change into an electric signal and take it out.

  Such a differential pressure sensor is used, for example, when measuring the liquid level height by detecting the differential pressure at two positions above and below in a closed tank that stores a fluid to be measured such as a high-temperature reaction tower in an oil refinery plant. Used.

  FIG. 5 shows a schematic configuration of a conventional differential pressure sensor. The differential pressure sensor 100 is configured by incorporating a sensor chip 1 having a sensor diaphragm (not shown) into a meter body 2. The sensor diaphragm in the sensor chip 1 is made of silicon, glass, or the like, and a strain resistance gauge is formed on the surface of the diaphragm formed in a thin plate shape. The meter body 2 includes a metal main body 3 and a sensor portion 4, and barrier diaphragms (pressure receiving diaphragms) 5 a and 5 b forming a pair of pressure receiving portions are provided on the side surfaces of the main body 3. A sensor chip 1 is provided in 4a.

  In the meter body 2, pressure buffer chambers 7 a and 7 b are separated by a large-diameter center diaphragm 6 between the sensor chip 1 provided in the sensor chamber 4 a and the barrier diaphragms 5 a and 5 b provided in the main body 3. Are connected to each other, and pressure transmission media 9a, 9b such as silicone oil are sealed in communication passages 8a, 8b connecting the sensor chip 1 and the barrier diaphragms 5a, 5b.

  The pressure medium such as silicone oil is required because it prevents the foreign matter in the measurement medium from adhering to the sensor diaphragm and does not corrode the sensor diaphragm. Therefore, the pressure receiving diaphragm has corrosion resistance and the sensor diaphragm has stress (pressure) sensitivity. This is because it is necessary to separate them.

  In this differential pressure sensor 100, as schematically shown in FIG. 6A, the operation state in a steady state, the measured pressure P1 from the process is applied to the barrier diaphragm 5a, and the measured pressure P2 from the process is applied to the barrier diaphragm. Applied to 5b. As a result, the barrier diaphragms 5a and 5b are displaced, and the applied pressures P1 and P2 are passed through the pressure transmission media 9a and 9b through the pressure buffering chambers 7a and 7b isolated by the center diaphragm 6, and the sensor of the sensor chip 1 They are guided to one side and the other side of the diaphragm, respectively. As a result, the sensor diaphragm of the sensor chip 1 exhibits a displacement corresponding to the differential pressure ΔP between the introduced pressures P1 and P2.

  On the other hand, for example, when an excessive pressure Pover is applied to the barrier diaphragm 5b, the barrier diaphragm 5b is greatly displaced as shown in FIG. 6B, and the center diaphragm 6 absorbs the excessive pressure Pover accordingly. It is displaced to. When the barrier diaphragm 5b settles on the bottom surface (overpressure protection surface) of the recess 10b of the meter body 2 and its displacement is restricted, transmission of a further differential pressure ΔP to the sensor diaphragm via the barrier diaphragm 5b. Is blocked. Even when an overpressure Pover is applied to the barrier diaphragm 5a, the barrier diaphragm 5a settles on the bottom surface (overpressure protection surface) of the recess 10a of the meter body 2 in the same manner as when the overpressure Pover is applied to the barrier diaphragm 5b. When the displacement is restricted, further transmission of the differential pressure ΔP to the sensor diaphragm via the barrier diaphragm 5a is prevented. As a result, damage to the sensor chip 1 due to application of the excessive pressure Pover, that is, damage to the sensor diaphragm in the sensor chip 1 is prevented in advance.

  In the differential pressure sensor 100, since the sensor chip 1 is included in the meter body 2, the sensor chip 1 can be protected from an external corrosive environment such as a process fluid. However, since the concave portion 10a, 10b for restricting the displacement of the center diaphragm 6 and the barrier diaphragms 5a, 5b is provided and the sensor chip 1 is protected from the excessive pressure Pover by these, the shape is increased. Inevitable.

  Therefore, by providing the sensor chip with a first stopper member and a second stopper member, the concave portions of the first stopper member and the second stopper member are opposed to one surface and the other surface of the sensor diaphragm, There has been proposed a structure that prevents excessive displacement of the sensor diaphragm when an excessive pressure is applied, thereby preventing damage or destruction of the sensor diaphragm (see, for example, Patent Document 1).

  FIG. 7 shows an outline of a sensor chip adopting the structure shown in Patent Document 1. In the figure, 11-1 is a sensor diaphragm, 11-2 and 11-3 are first and second stopper members joined with the sensor diaphragm 11-1 sandwiched therebetween, and 11-4 and 11-5 are stopper members 11. -2 and 11-3. The stopper members 11-2 and 11-3 and the pedestals 11-4 and 11-5 are made of silicon or glass.

  In this sensor chip 11, recesses 11-2a and 11-3a are formed in the stopper members 11-2 and 11-3, and the recess 11-2a of the stopper member 11-2 is connected to one of the sensor diaphragms 11-1. The concave portion 11-3a of the stopper member 11-3 is opposed to the other surface of the sensor diaphragm 11-1. The recesses 11-2a and 11-3a are curved surfaces (aspherical surfaces) along the displacement of the sensor diaphragm 11-1, and pressure introduction holes (pressure guide holes) 11-2b and 11-3b are formed at the tops thereof. Has been. Further, the pedestals 11-4 and 11-5 also have pressure introduction holes (pressure holes) 11-4a at positions corresponding to the pressure holes 11-2b and 11-3b of the stopper members 11-2 and 11-3. 11-5a are formed.

  When such a sensor chip 11 is used, when an excessive pressure is applied to one surface of the sensor diaphragm 11-1 and the sensor diaphragm 11-1 is displaced, the entire displacement surface is the recess 11 of the stopper member 11-3. -3a curved surface. When an excessive pressure is applied to the other surface of the sensor diaphragm 11-1 and the sensor diaphragm 11-1 is displaced, the entire displacement surface is received by the curved surface of the recess 11-2a of the stopper member 11-2.

  This prevents excessive displacement when an excessive pressure is applied to the sensor diaphragm 11-1, effectively preventing unintentional destruction of the sensor diaphragm 11-1 due to the application of the excessive pressure, and the overpressure protection operation. The pressure (pressure resistance) can be increased. Further, in the structure shown in FIG. 5, the center diaphragm 6 and the pressure buffering chambers 7a and 7b are eliminated, and the measurement pressures P1 and P2 are guided directly from the barrier diaphragms 5a and 5b to the sensor diaphragm 11-1. Thus, the meter body 2 can be miniaturized.

  In the structure for reducing the size of the meter body 2, as shown in FIG. 8, the sensor chip 11 is housed in the sensor chamber 4a, and the base 11-5 is joined to the bottom surface (wall surface) 4b of the sensor chamber 4a. Fixed by. In this case, the sensor diaphragm 11-1 is bent to the low pressure side in response to the differential pressure ΔP between the measured pressures P1 and P2 upon receiving the measured pressures P1 and P2. It is desirable that this bending be directed to the joint portion of the sensor chip 11 with the wall surface 4b of the sensor chamber 4a. When bending occurs in the opposite direction, the sensor chip 11 may be peeled off from the joint with the wall surface 4b of the sensor chamber 4a. The joint is pressed with a force F1 according to the product (S · P1) of the area S formed from the outer periphery of the joint with the wall surface 4b of the sensor chamber 4a and the measurement pressure P1. On the other hand, the joint portion is encapsulated in the joint portion with the wall surface 4b of the sensor chamber 4a and is joined by the force F2 corresponding to the product (X · P2) of the unjoined area X and the measurement pressure P2 connected to the measurement pressure P2. Torn apart. If the sum of the forces F3 and F1 at which the bonded portion alone maintains the bonding is not always increased by F2, the bonding is peeled off. The area S is larger in definition than the area X, and if P1 is larger than P2, the joint is not peeled off. Further, the same relationship is obtained at the joint portion between the sensor diaphragm 11-1 and the stopper member 11-3 in the sensor chip 11. For this reason, normally, the side that receives the pressure P1 is defined as the high pressure side, and the side that receives the pressure P2 is defined as the low pressure side.

JP 2005-69736 A

  However, in such a structure of the sensor chip 11, the height relationship between the pressure P1 and the pressure P2 can be reversed or the height relationship between the pressure P1 and the pressure P2 is not reversed. When installing, the operator may mistakenly select the pressure P1 side as the low pressure side and the pressure P2 side as the high pressure side. Separation of the joint portion of the sensor chip 11 with the wall surface 4b of the sensor chamber 4a and the joint portion of the multilayer structure in the sensor chip 11 cannot be prevented completely.

  The present invention has been made in order to solve such problems. The object of the present invention is to completely prevent peeling of the joint portion of the sensor chip, and to have a simple structure and miniaturization. It is to provide a possible differential pressure sensor.

  In order to achieve such an object, the present invention provides a sensor chip joined to a wall surface of a sensor chamber and a signal corresponding to a pressure difference provided on one surface and the other surface provided in the sensor chip. A sensor diaphragm for outputting, a first pressure receiving diaphragm for receiving a first measurement pressure, a second pressure receiving diaphragm for receiving a second measurement pressure, and a first measurement pressure received by the first pressure receiving diaphragm. A first pressure transmission medium that transmits to one surface of the sensor, a second pressure transmission medium that transmits a second measured pressure received by the second pressure receiving diaphragm to the other surface of the sensor diaphragm, and a sensor chamber A third pressure which is filled as a part of the chamber and applies a relatively high measurement pressure of the first measurement pressure and the second measurement pressure in a direction toward the joint of the sensor chip with the wall surface of the sensor chamber. Transmission A body, a third pressure receiving diaphragm that receives the first measured pressure in a branched manner, a fourth pressure receiving diaphragm that receives the second measured pressure in a branched manner, the sensor chamber, the enclosure chamber, the first and the second And a meter body provided with the third and fourth pressure receiving diaphragms, and the meter body includes first and second guides sealed with first and second pressure transmission media. The pressure path, the third and fourth pressure guiding paths for guiding the first and second measured pressures to the third and fourth pressure receiving diaphragms, and the space on the back side of the third pressure receiving diaphragm and the sensor chamber communicate with each other. A first communication path to be formed, and a second communication path for connecting the space on the back side of the fourth pressure receiving diaphragm and the sensor chamber to each other, and the space on the back side of the third and fourth pressure receiving diaphragms and the second communication path are formed. The first and second communication passages and the sensor chamber; The third pressure transmission medium the combined space as a filled chamber is characterized in that it is filled.

  In the present invention, the sensor chamber is filled with the third pressure transmission medium with the sensor chamber as a part of the enclosure chamber. In this sensor chamber, the third pressure transmission medium applies a relatively high measurement pressure of the first measurement pressure and the second measurement pressure in a direction toward the joint of the sensor chip with the wall surface of the sensor chamber. Work.

  That is, in the present invention, when the second measurement pressure is higher than the first measurement pressure, the fourth pressure receiving diaphragm is bent toward the back side, and the third pressure receiving diaphragm is opposite to the back side (front side). Side). Here, if the bending to the front side of the third pressure receiving diaphragm is restricted, the pressure of the third pressure transmission medium filled in the sensor chamber increases, and the second pressure higher than the first measurement pressure. The measured pressure of the sensor chip works in a direction toward the joint portion of the sensor chip with the wall surface of the sensor chamber. Further, when the first measurement pressure is higher than the second measurement pressure, the third pressure receiving diaphragm is bent toward the back side, and the fourth pressure receiving diaphragm is bent toward the side opposite to the back side (front side). Mu Here, if the bending to the front side of the fourth pressure receiving diaphragm is restricted, the pressure of the third pressure transmission medium filled in the sensor chamber increases, and the first pressure higher than the second measurement pressure. The measured pressure of the sensor chip works in a direction toward the joint portion of the sensor chip with the wall surface of the sensor chamber.

  As a result, the height relationship between the first measurement pressure and the second measurement pressure can be reversed, or the height relationship between the first measurement pressure and the second measurement pressure is not reversed, but it is installed on site. Even when the operator mistakenly selects the high-pressure side and the low-pressure side, always apply a force in the direction toward the joint with the wall of the sensor chamber to the sensor chip. Thus, it is possible to prevent peeling of the joint portion of the sensor chip (the joint portion of the sensor chip with the wall surface of the sensor chamber, the joint portion of the multilayer structure in the sensor chip).

  In the present invention, since the first pressure transmission medium and the second pressure transmission medium transmit the measurement pressure to one surface and the other surface of the sensor diaphragm, the detection accuracy of the differential pressure is affected. For this reason, the first pressure transmission medium and the second pressure transmission medium are used only for measurement purposes, and filling the sealed chamber including the sensor chamber with the third pressure transmission medium affects the measurement of the differential pressure. The measurement pressure is used without giving the sensor chip to prevent peeling of the joint portion of the sensor chip.

  Further, in the present invention, the first and second measurement pressures are formed in the meter body by forming the third and fourth pressure guide paths for guiding the first and second measurement pressures to the third and fourth pressure receiving diaphragms. The pressure does not need to be led directly from the outside of the meter body to the third and fourth pressure receiving diaphragms, and the pressure guiding pipe required for this can be reduced and a simple structure can be obtained.

  In the present invention, the first and second measured pressures are guided to the third and fourth pressure receiving diaphragms via the third and fourth pressure guiding paths inside the meter body. The measurement pressure may be supplied from the outside only to the side surface where the first and second pressure receiving diaphragms exist. For example, the meter body is a hexahedron having four side surfaces, and the first to fourth pressure receiving diaphragms are connected to the meter body. It is possible to reduce the size of the meter body by reducing the length of the side surface of the meter body by disposing one on each of the four side surfaces.

  According to the present invention, the sensor chamber is used as a part of the enclosure chamber and filled with the third pressure transmission medium, and the relatively high measurement pressure of the first measurement pressure and the second measurement pressure is supplied to the sensor of the sensor chip. Since it is made to work in the direction toward the junction with the wall surface of the chamber, the case where the height relationship between the first measurement pressure and the second measurement pressure can be reversed, or the first measurement pressure and the second measurement pressure The height relationship with the measured pressure does not reverse, but the wall of the sensor chamber always remains in relation to the sensor chip even if the operator mistakenly selects the high pressure side or the low pressure side when installing on the site. By applying a force in the direction toward the joint with the sensor chip, it is possible to completely prevent the sensor chip joint (the joint between the sensor chip and the wall of the sensor chamber, the joint of the multilayer structure in the sensor chip) from peeling off. It becomes possible to do.

  Further, according to the present invention, the first and second measured pressures are guided to the third and fourth pressure receiving diaphragms, and the third and fourth pressure guiding paths are formed in the meter body. It is not necessary to provide a pressure guiding pipe for guiding the second measurement pressure to the third and fourth pressure receiving diaphragms outside the meter body, and a simple structure can be achieved and the size can be reduced. For example, the meter body is a hexahedron having four side surfaces, and the first to fourth pressure receiving diaphragms are arranged one by one on the four side surfaces of the meter body, thereby reducing the length of the meter body side surface and reducing the size. Can be achieved.

It is a figure which shows the external appearance of one Embodiment of the differential pressure sensor which concerns on this invention. It is the longitudinal cross-sectional view which looked at this differential pressure sensor from the left front side (side 12D side) of a meter body. It is the longitudinal cross-sectional view which looked at this differential pressure sensor from the front side (side 12A side) of the meter body. It is a cross-sectional view (plane cross-sectional view) of this differential pressure sensor. It is a figure which shows schematic structure of the conventional differential pressure sensor. It is a figure which shows typically the operation | movement aspect of this differential pressure sensor. It is a figure which shows the outline of the sensor chip which employ | adopted the structure shown by patent document 1. FIG. It is a figure which shows the state which joined this sensor chip to the wall surface of the sensor chamber of a meter body.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a view showing an appearance of an embodiment of a differential pressure sensor according to the present invention. In the figure, 12 is a metal meter body, which is a hexahedron having four side surfaces 12A to 12D, an upper surface 12E, and a bottom surface 12F. In this example, the meter body 12 is a regular hexahedron (cube). However, the meter body 12 may be a hexahedron and may have any shape.

  FIG. 2 is a longitudinal sectional view of the differential pressure sensor 200 as viewed from the left side surface (side surface 12D side) of the meter body 12. FIG. 3 shows a longitudinal sectional view of the differential pressure sensor 200 as viewed from the front side (side surface 12A side) of the meter body 12. As shown in FIG. FIG. 4 shows a cross sectional view (plan sectional view) of the differential pressure sensor 200.

  In the differential pressure sensor 200, the meter body 12 is provided with a sensor chamber 12a in the upper part thereof. The sensor chip 11 is accommodated in the sensor chamber 12a, and the sensor chip 11 is fixed by joining the base 11-5 to the bottom surface (wall surface) 12b of the sensor chamber 12a.

  A pair of pressure receiving diaphragms 13 a and 13 b are provided on the side surfaces 12 </ b> A and 12 </ b> B of the meter body 12. The pressure receiving diaphragm 13a is a P1 side sensing pressure receiving diaphragm that receives the measurement pressure P1, and the pressure receiving diaphragm 13b is a P2 side sensing pressure receiving diaphragm that receives the measurement pressure P2. The meter body 12 has a recess 12c formed on the back side of the P1-side sensing pressure receiving diaphragm 13a, and a recess 12d formed on the back side of the P2-side sensing pressure receiving diaphragm 13b.

  A pair of pressure receiving diaphragms 14 a and 14 b are provided on the side surfaces 12 C and 12 D of the meter body 12. The pressure receiving diaphragm 14a is a P1 side protection pressure receiving diaphragm that branches and receives the measurement pressure P1, and the pressure receiving diaphragm 14b is a P2 side protection pressure receiving diaphragm that receives the measurement pressure P2 in a branched manner.

  It is desirable that the pressure receiving diaphragms 14a and 14b have as low rigidity as possible. The meter body 12 has a recess 12e formed on the back side of the P1 side protection pressure receiving diaphragm 14a, and a recess 12f formed on the back side of the P2 side protection pressure receiving diaphragm 14b.

  The P1 side protective pressure receiving diaphragm 14a is integrated with a P1 side protective pressure receiving diaphragm stopper 15a provided on the front side of the P1 side protective pressure receiving diaphragm 14a. The P1 side protective pressure receiving diaphragm 14a and the P1 side protective pressure receiving diaphragm 14a are integrated with each other. A P1 side protective pressure receiving diaphragm body storage chamber (circular step) formed on the side surface 12C of the meter body 12 as a P1 side protective pressure receiving diaphragm body 16a is a part integrated with the protective pressure receiving diaphragm stopper 15a (circular part). The opening surface of the P1 side protective pressure receiving diaphragm body storage chamber 17a into which the P1 side protective pressure receiving diaphragm body 16a is fitted is closed with a P1 side protective pressure receiving diaphragm body presser 18a. The P1 side protective pressure receiving diaphragm body presser 18a has a larger diameter than the P1 side protective pressure receiving diaphragm body 16a, and there is a space around the P1 side protective pressure receiving diaphragm body 16a in the P1 side protective pressure receiving diaphragm body storage chamber 17a. 19a is formed.

  The P1 side protective pressure receiving diaphragm stopper 15a includes a recess 15a1 facing the front surface of the P1 side protective pressure receiving diaphragm 14a, and a measurement medium of the measurement pressure P1 in a space 16a1 between the concave portion 15a1 and the P1 side protective pressure receiving diaphragm 14a. And a pressure introducing path (pressure guiding path) 15a2. The pressure guiding path 15a2 is formed on the surface of the P1 side protection pressure receiving diaphragm stopper 15a as a single groove extending from the outer peripheral edge to the center.

  A communication passage 12g (see FIG. 4) is formed in the meter body 12, and the periphery of the P1 side protection pressure receiving diaphragm body 16a in the P1 side protection pressure receiving diaphragm body storage chamber 17a is formed through the communication passage 12g. The measurement medium of the measurement pressure P1 flowing into the space 19a passes through the pressure guide path 15a2 formed on the surface of the P1 side protection pressure receiving diaphragm stopper 15a, and the concave portion 15a1 of the P1 side protection pressure receiving diaphragm stopper 15a and the P1 side Guided to the space 16a1 between the protective pressure receiving diaphragm 14a.

  The communication passage 12g formed inside the meter body 12 has one end immediately adjacent to the P1-side sensing pressure receiving diaphragm 13a provided on the side surface 12A of the meter body 12 (attaching a flange for guiding the measurement medium to the meter body 12). The other end is open to the surrounding space 19a in the P1 side protection pressure receiving diaphragm body storage chamber 17a in which the P1 side protection pressure receiving diaphragm body 16a is fitted.

  The P2 side protective pressure receiving diaphragm 14b is integrated with a P2 side protective pressure receiving diaphragm stopper 15b provided on the front side of the P2 side protective pressure receiving diaphragm 14b. A P2 side protective pressure receiving diaphragm body storage chamber (circular step) formed on the side surface 12D of the meter body 12 as a P2 side protective pressure receiving diaphragm body 16b is a part integrated with the protective pressure receiving diaphragm stopper 15b (circular part). The opening surface of the P2 side protective pressure receiving diaphragm body storage chamber 17b into which the P2 side protective pressure receiving diaphragm body 16b is fitted is closed with a P2 side protective pressure receiving diaphragm body presser 18b. The P2 side protective pressure receiving diaphragm body presser 18b has a larger diameter than the P2 side protective pressure receiving diaphragm body 16b, and there is a space around the P2 side protective pressure receiving diaphragm body 16b in the P2 side protective pressure receiving diaphragm body storage chamber 17b. 19b is formed.

  The P2-side protective pressure receiving diaphragm stopper 15b includes a concave portion 15b1 facing the front surface of the P2-side protective pressure-receiving diaphragm 14b, and a measurement medium of the measurement pressure P2 in the space 16b1 between the concave portion 15b1 and the P2-side protective pressure-receiving diaphragm 14b. And a pressure introducing path (pressure guiding path) 15b2 for guiding the. The pressure guiding path 15b2 is formed as a single groove on the surface of the P2 side protection pressure receiving diaphragm stopper 15b from the outer peripheral edge toward the center.

  A communication passage 12h (see FIG. 4) is formed inside the meter body 12, and the periphery of the P2-side protection pressure-receiving diaphragm body 16b in the P2-side protection pressure-receiving diaphragm body storage chamber 17b is formed through the communication passage 12h. The measurement medium of the measurement pressure P2 flowing into the space 19b passes through the pressure guiding path 15b2 formed on the surface of the P2 side protective pressure receiving diaphragm stopper 15b, and the concave portion 15b1 of the P2 side protective pressure receiving diaphragm stopper 15b and the P2 side Guided to the space 16b1 between the protective pressure receiving diaphragm 14b.

  The communication passage 12h formed inside the meter body 12 has one end directly adjacent to the P2 side sensing pressure receiving diaphragm 13b provided on the side surface 12B of the meter body 12 (attaching a flange for guiding the measurement medium to the meter body 12). The other end is open to the surrounding space 19b in the P2 side protective pressure receiving diaphragm body storage chamber 17b in which the P2 side protective pressure receiving diaphragm body 16b is fitted.

  In the meter body 12, a communication path 12i is formed between a recess 12c formed on the back side of the P1 sensing pressure receiving diaphragm 13a and the sensor chamber 12a. The communication path 12i is a wall surface 12b of the sensor chamber 12a. Through the inside of the sensor chip 11 joined to the sensor chip 11, the sensor chip 11 communicates with one surface (upper surface) of the sensor diaphragm 11-1 located at the center of the sensor chip 11. A pressure transmission medium 20a is sealed as a first pressure transmission medium in the communication path 12i including the recess 12c. That is, the first pressure transmission medium 20a is sealed with the communication path 12i including the recess 12c as the first pressure guiding path.

  The meter body 12 has a communication passage 12j formed between a recess 12d formed on the back side of the P2-side sensing pressure receiving diaphragm 13b and the sensor chamber 12a. The communication passage 12j is connected to the sensor chamber 12a. The sensor chip 11 joined to the wall surface 12b communicates with the other surface (lower surface) of the sensor diaphragm 11-1 located at the center of the sensor chip 11. A pressure transmission medium 20b is sealed as a second pressure transmission medium in the communication path 12j including the recess 12d. That is, the second pressure transmission medium 20b is sealed with the communication path 12j including the recess 12d as the second pressure guiding path.

  Further, the meter body 12 has a communication path 12k formed between the recess 12e formed on the back side of the P1 side protective pressure receiving diaphragm 14a and the sensor chamber 12a, and on the back side of the P2 side protective pressure receiving diaphragm 14b. A communication path 121 is formed between the formed recess 12f and the sensor chamber 12a. A space formed by combining the communication path 12k including the recess 12e, the communication path 12l including the recess 12f, and the sensor chamber 12a is formed as a sealed chamber by closing the opening on the upper surface of the sensor chamber 12 with the upper lid 21. The sealed chamber is filled with the pressure transmission medium 20c as a third pressure transmission medium (protective pressure transmission medium).

  In the differential pressure sensor 200, the measurement pressure P1 from the process is applied to the P1 side sensing pressure receiving diaphragm 13a, and the measurement pressure P2 from the process is applied to the P2 side sensing pressure receiving diaphragm 13b. As a result, the pressure sensing diaphragm 13a for P1 side sensing is displaced, and the measurement pressure P1 is guided to one surface of the sensor diaphragm 11-1 of the sensor chip 11 through the pressure transmission medium 20a in the communication path 12i. Further, the pressure sensing diaphragm 13b for P2 side sensing is displaced, and the measured pressure P2 is guided to the other surface of the sensor diaphragm 11-1 of the sensor chip 11 through the pressure transmission medium 20b in the communication path 12j. As a result, the sensor diaphragm 11-1 of the sensor chip 1 exhibits a displacement corresponding to the differential pressure ΔP between the derived measurement pressures P1 and P2.

  On the other hand, the measured pressure P1 to the P1 side sensing pressure receiving diaphragm 13a is supplied to the P1 side protecting pressure receiving diaphragm 17a in the P1 side protecting pressure receiving diaphragm body storage chamber 17a via the communication passage 12g formed in the meter body 12. The concave portion 15a1 of the P1 side protective pressure receiving diaphragm stopper 15a and the P1 side protective pressure receiving pressure flow into the space 19a around the body 16a and through the pressure guiding path 15a2 formed on the surface of the P1 side protective pressure receiving diaphragm stopper 15a. It is guided to the space 16a1 between the diaphragm 14a and applied to the P1 side protection pressure receiving diaphragm 14a.

  The measured pressure P2 to the pressure sensing diaphragm 13b for the P2 side sensing is applied to the pressure sensing diaphragm for P2 side protection in the P2 side pressure sensing diaphragm body storage chamber 17b via the communication passage 12h formed inside the meter body 12. The concave portion 15b1 of the P2 side protective pressure receiving diaphragm stopper 15b and the P2 side protective pressure receiving pressure flow into the space 19b around the body 16b, and through the pressure guiding path 15b2 formed on the surface of the P2 side protective pressure receiving diaphragm stopper 15b. It is guided to the space 16b1 between the diaphragm 14b and applied to the P2 side protection pressure receiving diaphragm 14b.

  In the differential pressure sensor 200 as well, as in the conventional differential pressure sensor, the joint of the sensor chip 11 (the joint of the sensor chip 11 with the wall surface 12b of the sensor chamber 12a, the joint of the multilayer structure in the sensor chip 11) is peeled off. From this point of view, the side receiving the pressure P1 is normally used as the high pressure side, and the side receiving the pressure P2 is used as the low pressure side.

  Therefore, normally, the measurement pressure P1 is higher than the measurement pressure P2. In this case, the P1 side protective pressure receiving diaphragm 14a bends to the back side, and the P2 side protective pressure receiving diaphragm 14b bends to the side opposite to the back side (front side). At this time, the P2 side protective pressure receiving diaphragm 14b is prevented from being excessively bent by the bottom surface of the recess 15b1 of the P2 side protective pressure receiving diaphragm stopper 15b. Thereby, the pressure of the pressure transmission medium 20c filled in the sensor chamber 12a increases, and the measurement pressure P1 higher than the measurement pressure P2 works in the direction toward the joint portion of the sensor chip 11 with the wall surface 12b of the sensor chamber 12a. It becomes.

  In contrast, the height relationship between the measurement pressure P1 and the measurement pressure P2 can be reversed, or the height relationship between the measurement pressure P1 and the measurement pressure P2 is not reversed. The high pressure side and the low pressure side may be selected by mistake. In this case, the measured pressure P2 to the differential pressure sensor 200 becomes higher than the measured pressure P1, the P2 side protective pressure receiving diaphragm 14b is bent to the back side, and the P1 side protective pressure receiving diaphragm 14a is opposite to the back side ( It bends to the front side. At this time, the P1 side protective pressure receiving diaphragm 14a is prevented from being excessively bent by the bottom surface of the recess 15a1 of the P1 side protective pressure receiving diaphragm stopper 15a. Thereby, the pressure of the pressure transmission medium 20c filled in the sensor chamber 12a increases, and the measurement pressure P2 higher than the measurement pressure P1 works in a direction toward the joint portion of the sensor chip 11 with the wall surface 12b of the sensor chamber 12a. It becomes.

  The bottom surface of the recess 15a1 of the P1 side protective pressure receiving diaphragm stopper 15a also serves as an overpressure protection surface of the P1 side protective pressure receiving diaphragm 14a when the measured pressure P2 is excessively higher than the measured pressure P1. The bottom surface of the concave portion 15b1 of the P2 side protection pressure receiving diaphragm stopper 15b also serves as an overpressure protection surface of the P2 side protection pressure receiving diaphragm 14b when the measurement pressure P1 is excessively higher than the measurement pressure P2.

  In this manner, in the differential pressure sensor 200 of the present embodiment, the pressure transmission medium 20c is filled with the sensor chamber 12a as a part of the sealed chamber, and the relatively high measurement pressure of the measurement pressure P1 and the measurement pressure P2. Is moved in the direction toward the joint portion of the sensor chip 11 with the wall surface 12b of the sensor chamber 12a, the case where the height relationship between the measurement pressure P1 and the measurement pressure P2 can be reversed, or the measurement pressure P1 Although the height relationship with the measurement pressure P2 is not reversed, even if the operator mistakenly selects the high pressure side and the low pressure side when installing on the site, the sensor chamber is always in the sensor chamber 11. A force in a direction toward the joint portion with the wall surface 12b of 12a is applied, and the joint portion of the sensor chip 11 (joint portion with the wall surface 12b of the sensor chamber 12a of the sensor chip 11 and multilayer in the sensor chip 11). Becomes the peeling of the concrete joint) is completely prevented.

  Further, in this differential pressure sensor 200, the communication passage 12g that leads the measurement pressure P1 to the P1 side protection pressure receiving diaphragm 14a and the communication passage 12h that leads the measurement pressure P2 to the P2 side protection pressure receiving diaphragm 14b are introduced to the measurement pressures P1 and P2. Since it is formed in the meter body 12 as a pressure path, it is not necessary to guide the measurement pressures P1 and P2 directly from the outside of the meter body 12 to the P1 side protection pressure receiving diaphragm 14a and the P2 side protection pressure receiving diaphragm 14b. The number of pressure guiding pipes can be reduced and the structure can be simplified.

  Further, in this differential pressure sensor 200, the measured pressures P1 and P2 are transferred to the P1 side protective pressure receiving diaphragm 14a and the P2 side protective pressure receiving diaphragm 14b via the communication paths (pressure guiding paths) 12g and 12h inside the meter body 12, respectively. Therefore, the measured pressures P1 and P2 of the fluid from the process may be supplied only to the side surfaces 12A and 12B where the P1 side sensing pressure receiving diaphragm 13a and the P2 side sensing pressure receiving diaphragm 13b exist.

  Accordingly, in the differential pressure sensor 200, the meter body 12 is a hexahedron having four side surfaces, the P1 side sensing pressure receiving diaphragm 13a is disposed on the side surface 12A of the meter body 12, and the P2 side sensing pressure receiving surface is disposed on the side surface 12B of the meter body 12. One pressure receiving diaphragm is provided on each of the four side surfaces, such as a diaphragm 13b, a P1 side protective pressure receiving diaphragm 14a on the side surface 12C of the meter body 12, and a P2 side protective pressure receiving diaphragm 14b on the side surface 12D of the meter body 12. By arranging them one by one, the length of the side surface of the meter body 12 can be reduced and the size can be reduced.

  In the differential pressure sensor 200, the P1 side protective pressure receiving diaphragm 14a and the P1 side protective pressure receiving diaphragm stopper 15a are integrated into a P1 side protective pressure receiving diaphragm body 16a. The P1 side protective pressure receiving diaphragm body 16a is used as the differential pressure sensor 200a. It is set in the P1 side protective pressure receiving diaphragm body storage chamber 17a and sealed in the P1 side protective pressure receiving diaphragm body storage chamber 17a by the P1 side protective pressure receiving diaphragm body presser 18a. Further, the P2 side protective pressure receiving diaphragm body 16b and the P2 side protective pressure receiving diaphragm stopper 15b are integrated into a P2 side protective pressure receiving diaphragm body 16b, and the P2 side protective pressure receiving diaphragm body 16b is used as the P2 side protective pressure receiving diaphragm body. It is set in the storage chamber 17b and sealed in the P2 side protection pressure receiving diaphragm body storage chamber 17b by the P2 side protection pressure receiving diaphragm body presser 18b. By adopting such a sealing structure, the concave portion 15a1 of the P1 side protective pressure receiving diaphragm body 15a and the P2 side protective pressure receiving diaphragm body 15b of the P1 side protective pressure receiving diaphragm body 16b and the P2 side protective pressure receiving diaphragm stopper 15b are provided. Only by controlling the depth of the recess 15b1, the bottoming distances of the P1 side protection pressure receiving diaphragm 14a and the P2 side protection pressure receiving diaphragm 14b can be controlled, and a desired pressure resistance can be reliably obtained. Become.

  In the differential pressure sensor 200, the concave portion 15a1 of the P1 side protective pressure receiving diaphragm stopper 15a plays a role of securing a bending allowance of the P1 side protective pressure receiving diaphragm 14a due to expansion of the pressure transmission medium 20c when the temperature changes. The concave portion 15b1 of the P2 side protection pressure receiving diaphragm stopper 15b plays a role of securing a bending allowance of the P2 side protection pressure receiving diaphragm 14b due to expansion of the pressure transmission medium 20c when the temperature changes.

  In the above-described embodiment, the sensor diaphragm 11-1 is a type in which a strain resistance gauge whose resistance value changes according to a pressure change is formed, but may be a capacitive sensor chip. A capacitance type sensor chip includes a substrate having a predetermined space (capacitance chamber), a diaphragm disposed in the space of the substrate, a fixed electrode formed on the substrate, and a movable electrode formed on the diaphragm. And. When the diaphragm is deformed by receiving pressure, the distance between the movable electrode and the fixed electrode changes, and the capacitance between them changes.

[Extension of the embodiment]
The present invention has been described above with reference to the embodiment, but the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 11-1 ... Sensor diaphragm, 11-2 ... 1st stopper member, 11-3 ... 2nd stopper member, 11-4, 11-5 ... Base, 12 ... Meter body, 12a ... Sensor chamber, 12b ... Bottom (Wall surface), 12c to 12f ... concave portion, 12g to 12l ... communication path, 13a ... pressure receiving diaphragm for P1 side sensing, 13b ... pressure receiving diaphragm for P2 side sensing, 14a ... pressure receiving diaphragm for P1 side protection, 14b ... for P2 side protection Pressure receiving diaphragm, 15a ... P1 side protecting pressure receiving diaphragm stopper, 15a1 ... recessed portion, 15a2 ... pressure introducing passage (pressure introducing passage), 15b ... P2 side protecting pressure receiving diaphragm stopper, 15b1 ... concave portion, 15b2 ... pressure introducing passage (pressure introducing) Road), 16a ... P1 side protection pressure receiving diaphragm body, 16b ... P2 side protection pressure receiving diaphragm body, 17a ... P1 Protective pressure-receiving diaphragm body storage chamber, 17b ... P2-side protective pressure-receiving diaphragm body storage chamber, 18a ... P1-side protective pressure-receiving diaphragm body holder, 18b ... P2-side protective pressure-receiving diaphragm body holder, 20a ... Pressure transmission medium (first Pressure transmission medium), 20b ... pressure transmission medium (second pressure transmission medium), 20c ... pressure transmission medium (third pressure transmission medium), 21 ... upper lid, 200 ... differential pressure sensor.

Claims (2)

A sensor chip bonded to the wall of the sensor chamber;
A sensor diaphragm that is provided in the sensor chip and outputs a signal corresponding to a pressure difference received on one surface and the other surface;
A first pressure receiving diaphragm for receiving a first measurement pressure;
A second pressure receiving diaphragm for receiving a second measured pressure;
A first pressure transmission medium for transmitting a first measurement pressure received by the first pressure receiving diaphragm to one surface of the sensor diaphragm;
A second pressure transmission medium for transmitting a second measured pressure received by the second pressure receiving diaphragm to the other surface of the sensor diaphragm;
The sensor chamber is filled as a part of a sealing chamber, and a relatively high measurement pressure of the first measurement pressure and the second measurement pressure is applied to a joint portion of the sensor chip with a wall surface of the sensor chamber. A third pressure transmission medium acting in the direction of travel;
A third pressure receiving diaphragm for receiving the first measurement pressure in a branched manner;
A fourth pressure receiving diaphragm for receiving the second measurement pressure in a branched manner;
The sensor chamber, the sealing chamber, the first and second pressure receiving diaphragms, and the meter body provided with the third and fourth pressure receiving diaphragms,
In the meter body,
First and second pressure guiding paths in which the first and second pressure transmission media are sealed;
Third and fourth pressure guiding paths for guiding the first and second measured pressures to the third and fourth pressure receiving diaphragms;
A first communication passage for communicating the space on the back side of the third pressure receiving diaphragm with the sensor chamber;
A second communication path for communicating the space on the back side of the fourth pressure receiving diaphragm and the sensor chamber;
The third pressure transmission medium is filled with a space obtained by combining the space on the back side of the third and fourth pressure receiving diaphragms, the first and second communication passages, and the sensor chamber as the enclosure chamber. A differential pressure sensor characterized by that. The differential pressure sensor according to claim 1,
The meter body is a hexahedron having four side surfaces,
The first to fourth pressure receiving diaphragms are:
One differential pressure sensor is provided on each of the four side surfaces of the meter body.

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